Manufacture of monomethyl-paraaminophenol and its sulphate



. sulphate, and more particularly to improvements Patented Dec. 7, 1937UNITED STATES PATENT oFFice MANUFACTURE OF MONOMETHYL-PARA- AMINOPHENOLAND ITS SULPHATE Simon Norman, Providence, E. I., assignor to IndustrialDyestuff Company, East Providence, R. 1., a corporation of Rhcde IslandNo Drawing. Original application July 30, 1935,

Serial No. 33,915. Divided and this application April 2'7, 1936, SerialNo. 76,696

16 Claims.

The instant case is a division of my earlier application, Serial Number33,915, filed July 30, 1935.

This invention relates to improvements in the manufacture ofN-methyl-para-aminophenol 201The proportions of these media employed aregenerally from ten to twelve times the Weight of the glycine.

It has been extremely dii'ficult to find media which are not required insuch large amounts in order to complete the decomposition ofthe glycinein a reasonable time andwhich do not resinify when heatedfor longperiods in contact with methylated aminophenoLflespecially when used inlarge scale production in the factory.

-It has also been diflicult to prevent decomposition ofN-methyl-para-aminophenol formed during the heat treatment.Decomposition of the N-methyl-para-aminophenol and resinificationseriously affect the yield of the finished N-methyl- -para-aminophenolsulphate, as well as the recovery of the media.

An object ofv the present invention is, therefore, to provide a processin which the aforesaid difliculties, particularly that of preventingresinification and that of preventing decomposition of the finalproduct, are overcome.

Another object is to provide a highly efficient process in whichpara-hydroxy-phenylglycine is decomposed under controlled conditions ina medium of such nature as to cause a rupture of the glycine grouping ata relatively low temperature and bring about the completion of thereaction in a relatively short time.

A further object is to provide a relatively inexpensive process by whichto carry on the above reaction, and which process permits of practicallycomplete recovery of the final product and of the media in which thereaction is carried out.

The media which are employed in the present process have been found tobe even more satisfactory than the products of the hydrogenation ofphenols, cresols, and their homologs, and they consist of a whole seriesof aliphatic ketones, or a mixture thereof.

I have found that any aliphatic ketone, preferably those containing onemethyl or ethyl group attached to the 0:0 linkage and boiling at C., orover, or mixtures of the same, having a resultant boiling range above145 C., will decompose para-hydroxy-phenylglycine satisfactorily andgive the resultant compound, monomethylparaaminophenol.

It has been found that the reactions herein disclosed require muchlesser amounts to effect the decomposition than any of the compoundsmentioned in the prior art, and still allow a very small amount ofby-products and impurities to form.

The following examples serve to illustrate the present invention:

Example 1.-Into'a suitable apparatus, charge 1 part, by weight ofpara-hydroxy-phenylglycine, 5 parts, by weight, of methyl-butylketone,and 5 parts, by weight, of methyl-hexylketone. The

mass is stirred and heated to attain a temperature'of from 140 C. to C.The temperature is now maintained at this point for a period of about 20minutes, after which time conversion occurs. The resulting product isnow cooled externally to about 25 C., whereupon it is diluted by theaddition of about 100 parts, by Weight, of ethyl alcohol and the wholewell mixed. The diluted mass is now treated with the stoichiometricamount of concentrated sulphuric acid, which causes the sulphate ofN-monomethyl-paraaminophenol to separate from the solution. Afterstirring the mass for a suitable period of time, it is filtered 011 andwashed with alcohol until the mother liquor has been removed. TheN-mono-methyl-para-aminophenol sulphate is obtained in excellent yieldand high purity.

Example 2.--1 part, by weight, of para-hydroXy-phenylglycine is mixedwith 5 parts, by weight, of methyl-propylketone, and 5 parts, by weight,of methyl-n-nonylketone. The temperature of the mixture is brought to150 C. to C., and it is converted in about 20 minutes. The process isthen finished by treating the mass as above. It will be noted, in thisexample, that a mixture of a low boiling ketone and a highboiling'ketone, to give a boiling range of from 150 C. to 160 C., gave asatisfactory result. Consequently, where the boiling point of the purealiphatic ketone is below 145 C., the addition of enough higher boilingketone will give a remethyl-para-aminophenol sultant boiling point inthe decomposition temperature range, and still give a satisfactoryresult.

What I claim is:

1. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing parahydroxy-phenylglycine to monoin reaction mediacontaining essentially a mixture of straight chain aliphatic ketoneshaving a resultant boiling point of at least 145 C.

2. A process as set forth in claim 1, wherein the mixture of ketonesincludes methyl-n-butylketone.

3. A process as set forth in claim 1, wherein the mixture of ketonesincludes methyl-n-hexylketone.

4. A process as set forth in claim 1, wherein the mixture of ketonesincludes essentially methyl-n-propylketone.

5. A process as set forth in claim 1, wherein the mixture of ketonesincludes methyl-n-nonylketone.

6. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing para-hydroxy-phenylglycine tomonomethyl-para-aminophenol in media containing essentiallymetiiyl-n-butylketone and methyl-nhexylketone.

7. In the process set forth in claim 6, the steps which consist inmixing 1 part, by weight, of para-hydroxy-phenylglycine, 5 parts, byweight, of methyl-n-butylketone, 5 parts, by weight, ofmethyl-n-hexylketone, heating the mixture to a temperature of 140 C. to150 0., for a period of about 20 minutes, diluting the resulting masswith alcohol, and adding sufficient sulphuric acid to convert themonomethyl-para-arninophenol base into monomethyl-para-aminophenolsulphate.

8. A process of manufacturing monomethylpara-aminophenol, whichcomprises decomposing para-hydroxy-phenylglycine tomonomethylpara-aminophenol in media containing essentiallymethyl-propylketone and methyl-n-nonylketone.

9. In the process set forth in claim 8, the steps which consist inmixing 1 part, by Weight, of para-hydroxy-phenylglycirie, 5 parts, byWeight, of methyl-propylketone, 5 parts, by weight, ofmethyl-n-nonylketone, heating the mixture to a temperature of 150 C. to160 C., for a period of about 20 minutes, diluting the resulting masswith alcohol, and adding sufficient sulphuric acid to convert themonomethyl-para-aminophenol base into monomethyl-para-aminophenolsulphate.

10. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing para-hydroxy-phenylglycine tomonomethyl-para-aminophenol in reaction media containing essentially astraight chain aliphatic ketone having a low boiling point and astraight chain aliphatic ketone having a higher boiling point, wherebythe resultant boiling point of the reaction mixture will be above 145 C.

11. A process of the character described, comprising decomposingpara-hydroxy-phenylglycine to monomethyl-para-aminophenol in reactionmedia, having a resultant boiling point of 'at least 145 C. andcontaining essentially a mixture of straight chain aliphatic ketones,and stirring the reaction mixture with a solution containing an amountof sulphuric acid suflicient to convert the monomethyl-para-aminophenolbase into vmonomethyl-para-aminophenol sulphate.

12. A process of the character described, comprising decomposingpara-hydroxy-phenylglycine to monomethyl-para-aminophenol in reactionmedia having a resultant boiling point of at least 145 C. and containingessentially a mixture of straight chain aliphatic ketones, diluting theresulting mass with alcohol, and adding sufficient sulphuric acid toconvert the monomethyl-paraaminophenol. into monomethyl-para-aminophenolsulphate.

13. In the process set forth in claim 12, the additional steps ofstirring the resulting mass for a period of about twenty minutes,filtering off and then washing off with alcohol until the mother liquorhas been removed.

14. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing para-hydroxy-phenylglycine tomonomethyl-para-aminophenol by means of heat in protecting mediacomprising essentially a mixture of straight chain aliphatic ketones andhaving a resultant boiling point of at least 145 C.

15. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing para-hydroxy-phenylglycine tomonomethyl-para-aminophenol in reaction media containing essentially amixture of non-cyclic aliphatic ketones having a resultant boiling pointof at least 145 C.

16. A process of manufacturing monomethylpara-aminophenol, which processcomprises decomposing para hydroxy-phenylglycine tomonomethyl-para-aminophenol in reaction media containing essentially amixture of non-cyclic aliphatic ketones having a resultant boiling pointof about 145 C.

SIMON NORMAN.

